Compressor, and refrigeration device

ABSTRACT

A compressor includes a casing that stores lubricating oil in a bottom of the casing, a compression mechanism housed in the casing, a housing that supports the compression mechanism and forms a crank chamber, a first oil return passage arranged to guide the lubricating oil flowing into the crank chamber downward, and a second oil return passage. The first oil return passage is provided with an oil return guide that contracts a flow of the lubricating oil. An upper portion of the casing forms an oil separation space that separates the lubricating oil from a high-pressure refrigerant discharged from the compression mechanism in the oil separation space. The second oil return passage guides the lubricating oil separated in the oil separation space downward, and an outlet of the second oil return passage is disposed near an outlet of the oil return guide.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a continuation of International Application No.PCT/JP2020/021574 filed on Jun. 1, 2020, which claims priority toJapanese Patent Application No. 2019-129494, filed on Jul. 11, 2019. Theentire disclosures of these applications are incorporated by referenceherein.

BACKGROUND Field of Invention

The present disclosure relates to a compressor and a refrigerationapparatus.

Background Information

WO2011/093385 discloses a compressor. In this compressor, mist-likelubricating oil, which is contained in a compressed refrigerant gasdischarged into a top space (a space in a casing above a compressionmechanism), is separated in a liquid state from the refrigerant gas bymeans of a centrifugal force generated by a swirling flow, therebyreducing oil loss.

In this compressor having a known structure, a static pressure in thetop space is lower than a static pressure of a space above a motor (aspace in the casing into which a high-pressure refrigerant gasdischarged downward from the compression mechanism flows). Thus, anegative pressure generated by contraction of the flow of therefrigerant gas flowing from the compression mechanism into the spaceabove the motor causes the lubricating oil separated in the top space toreturn from the top space to an oil reservoir at the bottom of thecasing via the space above the motor.

SUMMARY

A first aspect of the present disclosure is directed to a compressor,including a casing configured to store lubricating oil in a bottom ofthe casing, a compression mechanism housed in the casing, a housing thatsupports the compression mechanism and forms a crank chamber, a firstoil return passage arranged to guide the lubricating oil flowing intothe crank chamber downward, and a second oil return passage. The firstoil return passage is provided with an oil return guide that contracts aflow of the lubricating oil. An upper portion of the casing forms an oilseparation space configured to separate the lubricating oil from ahigh-pressure refrigerant discharged from the compression mechanismtherein. The second oil return passage is configured to guide thelubricating oil separated in the oil separation space downward, and anoutlet of the second oil return passage is disposed near an outlet ofthe oil return guide.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a refrigerant circuit of a refrigerationapparatus including a compressor according to an embodiment.

FIG. 2 is a longitudinal sectional view of the compressor according tothe embodiment.

FIG. 3 is a detailed longitudinal sectional view of an upper portion ofthe compressor shown in FIG. 2.

FIG. 4A is a perspective view illustrating an oil return guide of thecompressor shown in FIG. 2 as viewed from a drive shaft, and FIG. 4B isa perspective view illustrating the same as viewed from a casing.

FIG. 5A is a perspective view illustrating an oil return plate of thecompressor shown in FIG. 2 as viewed from the drive shaft, and FIG. 5Bis a perspective view illustrating the same as viewed from the casing.

FIG. 6 is a perspective view illustrating a compression mechanism,housing, and other adjacent components of the compressor shown in FIG. 2before a second oil return passage is attached.

FIG. 7 is a perspective view illustrating the compression mechanism,housing, and other adjacent components of the compressor shown in FIG. 2after the second oil return passage is attached.

FIG. 8A is a perspective view illustrating a variation of an internalrefrigerant discharge pipe of the compressor shown in FIG. 2 as viewedfrom the drive shaft, and FIG. 8B is a perspective view illustrating thesame as viewed from the casing.

DETAILED DESCRIPTION OF EMBODIMENT(S)

An embodiment of the present disclosure will be described below withreference to the drawings. The embodiment below is merely an exemplaryone in nature, and is not intended to limit the scope, applications, oruse of the invention.

Configuration of Refrigeration Apparatus

FIG. 1 is a schematic view illustrating a refrigerant circuit of arefrigeration apparatus (100) including a compressor (1) of the presentembodiment.

As illustrated in FIG. 1, the refrigeration apparatus (100) includes thecompressor (1) of the present embodiment, a condenser (2), an expansionmechanism (3), and an evaporator (4). The refrigeration apparatus (100)performs an operation of a refrigeration cycle in which a refrigerantcirculates in a refrigerant circuit shown in FIG. 1. Specifically, therefrigerant discharged from a discharge pipe (51) of the compressor (1)is introduced into a suction pipe (52) of the compressor (1) through thecondenser (2), the expansion mechanism (3), and the evaporator (4).

Configuration of Compressor

FIG. 2 is a longitudinal sectional view of the compressor (1) of thepresent embodiment, and FIG. 3 is a detailed longitudinal sectional viewillustrating an upper portion of the compressor (1) shown in FIG. 2. Thecompressor (1) is a scroll compressor configured to compress arefrigerant when at least one of two scroll parts meshing with eachother turns.

As illustrated in FIGS. 2 and 3, the casing (10) of the compressor (1)includes a substantially cylindrical barrel (11), a bowl-shaped top wallportion (12) hermetically welded to an upper end of the barrel (11), anda bowl-shaped bottom wall portion (13) hermetically welded to a lowerend of the barrel (11). The casing (10) is made of a rigid member thatis less likely to be deformed and damaged when pressure and temperatureinside and outside the casing (10) change. The casing (10) is placed sothat the axial direction of the substantially cylindrical barrel (11)extends along the vertical direction. The casing (10) houses, forexample, a compression mechanism (15) for compressing the refrigerant, adrive motor (21) disposed below the compression mechanism (15), and adrive shaft (24) disposed to extend vertically in the casing (10). Thedischarge pipe (51) and the suction pipe (52) for the refrigerant arehermetically joined to the casing (10). The refrigerant is introducedinto the casing (10) through the suction pipe (52), compressed in thecompression mechanism (15), and then discharged outside the casing (10)through the discharge pipe (51).

In the compressor (1), a space in the casing (10) between thecompression mechanism (15) and the drive motor (21) will be referred toas a space (S1) above the motor (herein referred to as “above-motorspace (S1)”), and a space in the casing (10) above the compressionmechanism (15) as an oil separation space (S2).

The compression mechanism (15) includes a fixed scroll part (16) and anorbiting scroll part (17). Each of the fixed scroll part (16) and theorbiting scroll part (17) is configured as an end plate and a spiral lapstanding upright on the end plate. The lap of the fixed scroll part (16)and the lap of the orbiting scroll part (17) mesh with each other toform a compression chamber enclosed by the laps and the end plates. Alid (41) is fastened to an upper surface of the fixed scroll part (16)with bolts (41 a) (see FIGS. 6 and 7). The fixed scroll part (16) has aninternal refrigerant discharge pipe (53) extending to an upper portionof the oil separation space (S2). The internal refrigerant dischargepipe (53) is an L-shaped pipe that extends vertically upward from thefixed scroll part (16), curves in the upper portion of the oilseparation space (S2), and extends horizontally along a ceiling of thecasing (10).

A housing (18) is disposed below the compression mechanism (15), and anouter peripheral surface of the housing (18) is joined to an inner wallof the casing (10). The fixed scroll part (16) is placed on the housing(18) by, e.g., bolt fixing. The housing (18) and the fixed scroll part(16) sandwich the orbiting scroll part (17) with an Oldham coupling (42)interposed therebetween. The housing (18) forms a crank chamber (19).The housing (18) has a bearing (20) that supports an upper portion ofthe drive shaft (24) below the crank chamber (19). The housing (18) isprovided with a refrigerant passage (18 a) connected to the lower end ofthe internal refrigerant discharge pipe (53) and communicates with theabove-motor space (S1).

In the present embodiment, the refrigerant introduced into thecompression mechanism (15) through the suction pipe (52) is compressedand delivered to the above-motor space (S1) above the motor, passesthrough the refrigerant passage (18 a), the internal refrigerantdischarge pipe (53), and the oil separation space (S2), and isdischarged outside the casing (10) from the discharge pipe (51) (seeopen arrows drawn with a broken line in FIGS. 2 and 3).

The drive motor (21) is, for example, a brushless DC motor, and isdisposed below the housing (18). The drive motor (21) includes a stator(22) fixed to the inner wall of the casing (10) and a rotor (23)rotatably housed inside the stator (22) with a slight gap left betweenthe rotor (23) and the stator (22). The rotor (23) is connected to theorbiting scroll part (17) at its center of rotation via the drive shaft(24). A frame (25) is fixed to the barrel (11) of the casing (10) andsupports a lower portion of the drive shaft (24) below the drive motor(21). An oil separation plate (25 a) is placed on an upper surface ofthe frame (25) to separate lubricating oil contained in the compressedrefrigerant descending from the compression mechanism (15). Theseparated lubricating oil drops into an oil reservoir (P) at the bottomof the casing (10).

The drive shaft (24) connects the compression mechanism (15) and thedrive motor (21) to each other, and extends vertically in the casing(10). The lower end of the drive shaft (24) is located in the oilreservoir (P). An oil supply passage (not shown) is formed inside thedrive shaft (24) to penetrate the drive shaft (24) in the axialdirection. When the drive shaft (24) rotates about its axis, an oil pump(e.g., a trochoid pump) disposed at the lower end of the drive shaft(24) causes the lubricating oil stored in the oil reservoir (P) to flowupward in the oil supply passage, thereby lubricating sliding portions(e.g., pin bearings) of the compression mechanism (15). Horizontal oilsupply holes (not shown) for supplying the lubricating oil to thesliding portions, such as the bearing (20), are formed inside the driveshaft (24) to be connected to the oil supply passage. The lubricatingoil flowing upward in the oil supply passage is supplied to thehorizontal oil supply holes to lubricate the sliding portions of thedrive shaft (24).

Configuration of Lubricating Oil Recovery Mechanism

A mechanism for recovering the lubricating oil supplied to lubricate thesliding portions of the compression mechanism (15) and the drive shaft(24) will be described below.

The lubricating oil used to lubricate the sliding portions of thecompression mechanism (15) flows into the crank chamber (19), and isthen guided downward through a first oil return passage (31) asillustrated in FIGS. 2 and 3 (see open arrows drawn with a solid line inFIGS. 2 and 3). The first oil return passage (31) is provided with anoil return guide (32) that contracts the flow of the lubricating oil. Atleast a lower portion of the oil return guide (32) is surrounded by aninner wall surface of the casing (10) and an oil return plate (35)extending downward along the inner wall surface. The lubricating oildelivered from an outlet of the oil return guide (32) descends in thespace surrounded by the oil return plate (35) and the inner wall surfaceof the casing (10), and returns to the oil reservoir (P) at the bottomof the casing (10).

FIG. 4A is a perspective view illustrating the oil return guide (32) asviewed from the drive shaft (24), and FIG. 4B is a perspective viewillustrating the same as viewed from the casing (10). As illustrated inFIGS. 4A and 4B, the oil return guide (32) has a connection hole (32 a)connected to the crank chamber (19), and a flow contraction portion (32b) extending downward along the inner wall surface of the casing (10),or of the barrel (11). The flow contraction portion (32 b) may be shapedwider in a circumferential direction, than in a radial direction, of thecylindrical casing (10). The flow contraction portion (32 b) may have aradial dimension of, for example, about 2 mm to 3 mm, and acircumferential dimension of, for example, about 10 mm.

FIG. 5A is a perspective view illustrating the oil return plate (35) asviewed from the drive shaft (24), and FIG. 5B is a perspective viewillustrating the same as viewed from the casing (10). As illustrated inFIGS. 5A and 5B, the oil return plate (35) includes a surroundingportion (32 b) surrounding at least a lower portion (the flowcontraction portion (35 a)) of the oil return guide (32) from the sideof the drive shaft (24), and a fixed portion (35 b) fixed to the innerwall surface of the casing (10). The surrounding portion (35 a) may beshaped such that a space between the surrounding portion (35 a) and theinner wall surface of the casing (10) narrows downward from the vicinityof an outlet of the oil return guide (32). The fixed portion (35 b) mayhave a shape corresponding to the inner wall surface of the casing (10).

The oil used to lubricate the teeth of the fixed scroll part (16) andthe end plate of the orbiting scroll part (17), i.e., a thrust bearing,leaks into the compression chamber during a compression stroke, mergeswith the lubricating oil originally circulating in the system, and isdischarged together with the compressed refrigerant from the compressionchamber to the above-motor space (S1). The lubricating oil in thecompressed refrigerant is in the form of mist.

A portion of the lubricating oil contained in the descending compressedrefrigerant is separated by the oil separation plate (25 a) and returnsto the oil reservoir (P) at the bottom of the casing (10) as describedabove. The rest of the lubricating oil passes through the oil separationspace (18 a) and the internal refrigerant discharge pipe (53) and isdischarged to the refrigerant passage (S2) together with the compressedrefrigerant (see the open arrows drawn with a broken line in FIGS. 2 and3). The compressed refrigerant is discharged to the oil separation space(S2) along the tangential direction of the internal wall surface of thecasing (10) (top wall portion (12)), and the discharged compressedrefrigerant swirls along the internal wall surface of the top wallportion (12) in the oil separation space (S2) (see a broken line arrow Fin FIG. 3). At this time, the lubricating oil contained in thecompressed refrigerant is scattered toward the inner wall surface of thetop wall portion (12) under the centrifugal force generated by theswirling flow, and collides with the inner wall surface of the top wallportion (12). The lubricating oil that has collided and turned to aliquid film falls along the inner wall surface of the top wall portion(12), and is discharged from an upper oil discharge hole (16 a) formedin the fixed scroll part (16) to the above-motor space (S1) through asecond oil return passage (33) (see the open arrows drawn with a solidline in FIGS. 2 and 3). The compressed refrigerant from which thelubricating oil has been separated in the oil separation space (S2) isdischarged outside the casing (10) through the discharge pipe (51).

In the present embodiment, a pipe (34) penetrating the fixed scroll part(16) and the housing (18) constitutes the second oil return passage(33). The pipe (34) has an inner diameter of, for example, about 2 mm.

FIG. 6 is a perspective view illustrating the compression mechanism(15), the housing (18), and other adjacent components before the secondoil return passage (33), i.e., the pipe (34), is attached, and FIG. 7 isa perspective view illustrating the same after the second oil returnpassage (33), i.e., the pipe (34), is attached.

As illustrated in FIGS. 2, 3, 6, and 7, the fixed scroll part (16) isprovided with the upper oil discharge hole (16 a) vertically penetratingthe fixed scroll part (16), and the housing (18) is provided with alower oil discharge hole (18 b) that vertically penetrates the housing(18) and is connected to the upper oil discharge hole (16 a). The pipe(34) serving as the second oil return passage (33) is inserted into theupper oil discharge hole (16 a) and the lower oil discharge hole (18 b).The lower portion of the pipe (34) protrudes in the above-motor space(S1) below the housing (18), and a lower end of the pipe (34), i.e., anoutlet of the second oil return passage (33), is disposed near theoutlet of the oil return guide (32). The oil return plate (35) isdisposed to surround, together with the inner wall surface of the casing(10), at least the lower portion of the oil return guide (32) and atleast the lower portion of the pipe (34). Thus, the lubricating oildelivered from the lower end of the pipe (34), i.e., the outlet of thesecond oil return passage (33), descends in the space surrounded by theoil return plate (35) and the inner wall surface of the casing (10), andreturns to the oil reservoir (P) at the bottom of the casing (10).

The oil return plate (35) may be shaped such that the space between theoil return plate (35) and the inner wall surface of the casing (10)narrows downward from the vicinity of the outlets of the oil returnguide (32) and the pipe (34).

Advantages of Embodiment

In the compressor (1) of the embodiment described above, the outlet ofthe second oil return passage (33) for the lubricating oil separated inthe oil separation space (S2) in the upper portion of the casing (10) isdisposed near the outlet of the oil return guide (32) that contracts theflow of the lubricating oil discharged downward from the crank chamber(19). This configuration can guide the lubricating oil separated in theoil separation space (S2) downward through the second oil return passage(33) under the negative pressure generated not by the contraction of theflow of the refrigerant gas, but by the contraction of the flow of thelubricating oil. Thus, the lubricating oil separated in the oilseparation space (S2) does not merge into the flow of the refrigerantgas again, reducing the oil loss more effectively.

More specifically, the oil that has lubricated the sliding portions (pinbearing, upper main bearing, etc.) of the compression mechanism (15) andthe drive shaft (24) once flows into the crank chamber (19), and thenreturns to the oil reservoir (P) through the oil return guide (32) andthe oil return plate (35). When the lubricating oil is guided from thecrank chamber (19) to the oil return guide (32), the oil flow iscontracted. In particular, a static pressure of a space around theoutlet of the oil return guide (32) surrounded by the oil return plate(35) is lower than static pressures of the above-motor space (S1) andthe oil separation space (S2). Thus, when the outlet of the second oilreturn passage (33) is disposed near the outlet of the oil return guide(32), the oil in a liquid state separated in the top space serving asthe oil separation space (S2) is discharged into the space surrounded bythe oil return plate (35) through the second oil return passage (33),i.e., the pipe (34), and returns to the oil reservoir (P) as it is.

Specifically, the compressor (1) having the top space serving as the oilseparation space (S2) contracts the flow of the oil discharged from thecrank chamber (19), and allows a region where the contraction occurs andthe oil separation space (S2) to communicate with each other through thesecond oil return passage (33). Thus, the separated oil can return tothe oil reservoir (P) together with the flow of the discharged oil. Thiscan reduce the oil loss of the compressor (1) more effectively.

As described above, the compressor (1) of the present embodiment canreduce the oil loss more effectively than a known compressor in whichliquid oil separated in the top space is discharged into the dischargedrefrigerant gas. The top space serving as the oil separation space (S2)basically separates the oil as effectively as a known oil separator thatis independently provided. Thus, the compressor (1) can be providedwithout such an oil separator, reducing the cost and size of anair-conditioning system such as a refrigeration apparatus.

When the compressor (1) of the present embodiment includes the pipe (34)passing through the housing (18) as the second oil return passage (33),the structure of the second oil return passage (33) can be simplified.

The compressor (1) of the present embodiment further includes an oilreturn plate (35) disposed to surround, together with the inner wallsurface of the casing (10), at least a lower portion of the second oilreturn passage (33) and at least a lower portion of the oil return guide(32). This configuration can keep the lubricating oil delivered from theoutlets of the second oil return passage (33) and the oil return guide(32) from scattering. In this case, when a space surrounded by the oilreturn plate (35) and the inner wall surface of the casing (10) narrowsdownward from the vicinity of the outlets of the second oil returnpassage (33) and the oil return guide (32), the lubricating oil flowsfaster as it goes downward. This can efficiently guide the lubricatingoil downward.

Other Embodiments

In the above embodiment, the compressor (1) having the configurationshown in

FIG. 2 has been described. In the present disclosure, however, thecompressor is not limited to have such a configuration as long as thetop space is used as the oil separation space and the lubricating oil isstored in the bottom. For example, the shape of the oil return guide(32) shown in FIGS. 4A and 4B and the shape of the oil return plate (35)shown in FIGS. 5A and 5B are merely examples, and the oil return guide(32) and the oil return plate (35) are not limited to have these shapes.

In the above embodiment, the whole second oil return passage (33) isformed of the pipe (34). However, the upper oil discharge hole (16 a)and the lower oil discharge hole (18 b) may be used as part of thesecond oil return passage (33) as they are. Alternatively, the secondoil return passage (33) having no upper oil discharge hole (16 a) may beformed without providing the fixed scroll part (16) on the lower oildischarge hole (18 b) of the housing (18).

Instead of the oil return plate (35) disposed in the above embodiment,for example, the oil return guide (32) and the pipe (34) may furtherextend downward to eliminate the need of the oil return plate (35).

In place of a circular tube extending in an L-shape arranged as theinternal refrigerant discharge pipe (53) of the above embodiment, forexample, a sheet metal member (54) as shown in FIGS. 8A and 8B may beattached to the inner wall of the top wall portion (12) to serve as theinternal refrigerant discharge pipe. FIG. 8A is a perspective viewillustrating the sheet metal member (54) as viewed from the drive shaft,and FIG. 8B is a perspective view illustrating the same as viewed fromthe casing. As illustrated in FIGS. 8A and 8B, the sheet metal member(54) has a pipe wall portion (54 a) that forms a conduit serving as theinternal refrigerant discharge pipe between the pipe wall portion (54 a)and the internal wall of the top wall portion (12), and a fixed portion(54 b) fixed to the internal wall surface of the top wall portion (12).The pipe wall portion (54 a) may extend vertically upward from the fixedscroll part (16), curve in an upper portion of the oil separation space(S2), and extend horizontally. The fixed portion (54 b) may have a shapecorresponding to the inner wall surface of the top wall portion (12).

While the embodiments have been described above, it will be understoodthat various changes in form and details can be made without departingfrom the spirit and scope of the claims. The embodiment and otherembodiments may be combined and replaced with each other withoutdeteriorating intended functions of the present disclosure. Theexpressions of “first” and “second” described above are used todistinguish the terms to which these expressions are given, and do notlimit the number and order of the terms.

The present disclosure is useful for a compressor and a refrigerationapparatus.

1. A compressor comprising: a casing configured to store lubricating oilin a bottom of the casing; a compression mechanism housed in the casing;a housing that supports the compression mechanism and forms a crankchamber; a first oil return passage arranged to guide the lubricatingoil flowing into the crank chamber downward, the first oil returnpassage being provided with an oil return guide that contracts a flow ofthe lubricating oil; and a second oil return passage, an upper portionof the casing forming an oil separation space configured to separate thelubricating oil from a high-pressure refrigerant discharged from thecompression mechanism therein, the second oil return passage beingconfigured to guide the lubricating oil separated in the oil separationspace downward, and an outlet of the second oil return passage beingdisposed near an outlet of the oil return guide.
 2. The compressor ofclaim 1, wherein the second oil return passage includes a pipe thatpenetrates the housing.
 3. The compressor of claim 1, furthercomprising: an oil return plate disposed to surround, together with aninner wall surface of the casing, at least a lower portion of the secondoil return passage and at least a lower portion of the oil return guide.4. The compressor of claim 2, further comprising: an oil return platedisposed to surround, together with an inner wall surface of the casing,at least a lower portion of the second oil return passage and at least alower portion of the oil return guide.
 5. The compressor of claim 3,wherein a space surrounded by the oil return plate and the inner wallsurface of the casing narrows downward from a vicinity of the outlets ofthe second oil return passage and oil return guide.
 6. A refrigerationapparatus including the compressor of claim
 1. 7. A refrigerationapparatus including the compressor of claim
 2. 8. A refrigerationapparatus including the compressor of claim
 3. 9. A refrigerationapparatus including the compressor of claim 5.